1. Field of the Invention
The present invention relates to an ink, and an ink-jet recording method and instruments making use of the ink, and more specifically to an ink which can provide prints excellent in water resistance and conduct recording on non-coated paper such as woodfree paper, medium-quality paper, bond paper and regenerated paper, i.e., so-called plain paper, which are commonly used in offices, and also on other recording materials, and an ink-jet recording method and instruments making use of such an ink.
2. Related Background Art
Inks with greatly various manners of being composed have been hitherto reported in respect of inks for writing utensils (fountain pens, marking pens, ball-point pens making use of a water-based ink, etc.) and for ink-jet recording. In particular, in recent years, detailed researches and developments have been made from various aspects such as compositions and physical properties of inks so that good recording can be conducted even on plain paper such as paper for copying, paper for reporting, notepaper, letter paper, bond paper and continuous business forms, which have been commonly used in offices.
For example, Japanese Patent Application Laid-Open No. 58-80366 has proposed a water-based ink in which an imide compound has been contained in a water-based ink composition so as to achieve the prevention of clogging of a nozzle part and to provide images excellent in print quality.
Even in such an ink which can provide prints with high quality, however, the following problem has been encountered: The resulting print is poor in water resistance because the ink is soluble in water, so that when waterdrops such as raindrops adhere to the print, or the print is immersed in water after printing, the ink runs out, resulting in deteriorated image density. In particular, a water-based ink for ink-jet recording, which serves to provide color images, is all the more likely to run because a dye having high solubility in water is used in order to make the chromaticity of the ink high.
Further, since water and low-boiling solvents are used in water-soluble ink compositions, such solvents vaporize as the time goes on when such ink compositions are stored for a long period of time, so that the viscosity of the ink compositions becomes higher. Accordingly, there is also a problem that such ink compositions become unsuitable for use in ink-jet recording which is constituted so as to eject an ink out of a minute orifice or orifices, resulting in uneven ink droplets.